<template>
    <div class="sidebar">
        <el-menu
            class="sidebar-el-menu"
            :default-active="onRoutes"
            :collapse="collapse"
            background-color="#324157"
            text-color="#bfcbd9"
            active-text-color="#20a0ff"
            unique-opened
            router
        >
            <template v-for ="item in items">
                <template v-if="item.subs">
                    <el-submenu :index="item.index" :key="item.index">
                        <template slot="title">
                            <i :class="item.icon"></i>
                            <span slot="title">{{item.title}}</span>
                        </template>
                        <template v-for="subItem in item.subs">
                            <!-- 判断是否有3级菜单 -->
                            <el-submenu
                                v-if="subItem.subs"
                                :index="subItem.index"
                                :key="subItem.index"
                            >
                                <template slot="title">
                                    {{subItem.title}}
                                </template>
                                <el-menu-item
                                    v-for="(threeItem, i) in subItem.subs"
                                    :key="i"
                                    :index="threeItem.index"
                                >
                                    {{threeItem.title}}
                                </el-menu-item>
                            </el-submenu>
                            <el-menu-item
                                v-else
                                :index="subItem.index"
                                :key="subItem.index"
                            >
                                {{subItem.title}}
                            </el-menu-item>
                        </template>
                    </el-submenu>
                </template>
                <template v-else>
                    <el-menu-item :index="item.index" :key="item.index">
                        <i :class="item.icon"></i>
                        <span slot="title">{{item.title}}</span>
                    </el-menu-item>
                </template>
            </template>
        </el-menu>
    </div>
</template>

<script>
    import bus from 'utils/bus.js'
    export default {
        name : 'Sidebar',
        data() {
            return {
                collapse: false,
                items: [
                    {
                        icon: 'el-icon-s-home',
                        index: 'dashboard',
                        title: '系统首页'
                    },
                    {
                        icon: 'el-icon-s-grid',
                        index: 'table',
                        title: '基础表格'
                    },
                    {
                        icon: 'el-icon-s-order',
                        index: 'tabs',
                        title: 'tab选项卡'
                    },
                    {
                        icon: 'el-icon-date',
                        index: '3',
                        title: '表单相关',
                        subs: [
                            {
                                index: 'form',
                                title: '基本表单'
                            },
                            {
                                index: '3-2',
                                title: '三级菜单',
                                subs: [
                                    {
                                        index: 'editor',
                                        title: '富文本编辑器'
                                    },
                                    {
                                        index: 'markdown',
                                        title: 'markdown编辑器'
                                    }
                                ]
                            },
                            {
                                index: 'upload',
                                title: '文件上传'
                            }
                        ]
                    },
                    {
                        icon: 'el-icon-magic-stick',
                        index: 'icon',
                        title: '自定义图标'
                    },
                    {
                        icon: 'el-icon-pie-chart',
                        index: 'charts',
                        title: 'schart图表'
                    },
                    {
                        icon: 'el-icon-rank',
                        index: '6',
                        title: '拖拽组件',
                        subs: [
                            {
                                index: 'drag',
                                title: '拖拽列表'
                            }
                        ]
                    },
                    {
                        icon: 'el-icon-warning',
                        index: '7',
                        title: '错误处理',
                        subs: [
                            {
                                index: '403',
                                title: '403页面'
                            },
                            {
                                index: '404',
                                title: '404页面'
                            }
                        ]
                    }
                ]
            };
        },
        computed: {
            // :default-active="onRoutes"
            // 这样写很重要，可以通过路由来控制激活的side，tags的改变也会改变default-active
            onRoutes() {
                return this.$route.path.replace('/', '');
            }
        },
        created () {
            bus.$on('collapse', msg => {
                this.collapse = msg;
                // 让盒子宽度变换
                bus.$emit('collapse-content', msg);
            })
        }
    }
</script>

<style scoped>
    .sidebar {
        display: block;
        position: absolute;
        left: 0;
        top: 70px;
        bottom: 0;
        overflow-y: scroll;
    }

    .sidebar::-webkit-scrollbar {
        width: 0;
    }

    .sidebar-el-menu:not(.el-menu--collapse) {
        width: 250px;
    }

    .sidebar > ul {
        height: 100%;
    }
</style>